The following link may not work as a "hot" link. If it doesn't, simply copy and paste it into your browser. http://auto.howstuffworks.com/framed.htm? parent=question164.htm&url=http://www.vtr.org/maintain/oil- overview.html Bruce W. Schug CORSA South Carolina Greenville, SC bwschug@charter.net CORSA member since 1981 '67 Monza. "67AC140"